21818208 has 96 divisors (see below), whose sum is σ = 62868960. Its totient is φ = 6594560.

The previous prime is 21818207. The next prime is 21818221. The reversal of 21818208 is 80281812.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21818201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47098 + ... + 47558.

It is an arithmetic number, because the mean of its divisors is an integer number (654885).

Almost surely, 2^21818208 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21818208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31434480).

21818208 is an abundant number, since it is smaller than the sum of its proper divisors (41050752).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21818208 is a wasteful number, since it uses less digits than its factorization.

21818208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520 (or 512 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 30.

The square root of 21818208 is about 4670.9964675645. The cubic root of 21818208 is about 279.4299968801.

The spelling of 21818208 in words is "twenty-one million, eight hundred eighteen thousand, two hundred eight".